1. Field of the Invention
This invention relates to a surface-sensing device for use in position-determining apparatus such as, for example a coordinate measuring machine or machine tool.
Such a machine is used for measuring a workpiece, and typically comprises a head moveable in three directions x, y, z, relative to a table on which the workpiece is supported. Movement of the head in each of the directions relative to a datum provided on the table is measured by scales on the machine, and a probe provided on the head emits a signal indicating the relationship between the workpiece surface to be measured, and the head. The position of the surface may thus be determined.
It is sometimes desirable to obtain continuous data on the position of a surface, i.e., to scan the profile of a surface with the machine, rather than simply obtain data in the form of one or more discrete points.
2. Description of Related Art
To achieve this, a measuring probe is provided on the head. The probe supports a stylus for movement relative to the head, and measures the magnitude of the stylus movement relative to the head in the x, y, z directions. The head may therefore move adjacent the surface to be scanned while the stylus is in contact with the surface, and the surface profile may thus be determined. An example of such a probe is shown in U.S. Pat. No. 3,869,799.